The present invention relates to noise abatement apparatuses and, more particularly, is directed to apparatuses and methods for reducing the emission of noise from an appliance such as an automatic clothes washing machine or a refrigerator.
Over the years, many machines have been developed for simplifying household activities and for making such activities less time consuming. For example, the processes and apparatuses used to wash articles of clothing have evolved over the years from the utilization of wash boards and machines equipped with hand powered agitators to the use of electrically powered washing machines having sophisticated washing cycles adapted to accommodate a variety of different clothing materials.
A typical clothes washing machine includes a cabinet that is fashioned from relatively thin metal and typically has an open bottom. A wash basket is rotatably supported within a watertight tub that is located within the cabinet and is adapted to be rotated by an electric motor housed within the cabinet. An access door is provided in the upper surface of the cabinet to provide access to the basket. An agitator is centrally disposed within the basket and is rotatably driven in a back and forth manner to agitate the clothes during various machine cycles. Water is selectively pumped into and drained from the tub at various intervals by a pump mounted within the cabinet. The user typically adds a cleaning medium (e.g., liquid or granular detergents) prior to the commencement of the cleaning cycle.
Most, if not all, commercially available clothes washing machines are equipped with electrical controls that govern various cleaning cycles. For example, after the clothes and detergent have been placed in the basket, a typical first cycle involves the addition of a predetermined amount of water to the tub. The operator can generally select between cold or heated water. After the water has been introduced into the wash tub, an agitating cycle typically begins. Upon completion of the agitating cycle, the water/detergent mixture is drained from the tub. Clean rinse water is then typically added to the tub and the agitation cycle is re-commenced to remove any remaining detergent/dirt from the clothing and tub. Thereafter, the rinse water is drained from the tub. In many clothes washers, the basket is then rapidly spun to assist with the removal of water from the clothing.
Perhaps anyone who is familiar with such washing machines is aware that they tend to generate a large amount of noise throughout their various cycles of operation. The magnitude of such noise can be dependent upon the location of the various machine components such as the pump and motors within the cabinet.
In an effort to reduce the amount of noise emitted from the bottom of the cabinet, shielding plate assemblies have been developed which form an integral portion of the cabinet bottom. Examples of such apparatuses are disclosed in U.S. Pat. No. 5,056,341 and U.S. Pat. No. 5,515,702. Similarly, U.S. Pat. Nos. 4,007,388 and 3,773,140 disclose integral noise reduction systems for large industrial machinery.
Other attempts at noise abatement have involved covering the interior surfaces of the cabinet walls with insulation. However, such methods are not particularly effective and have certain disadvantages. It is known that sound energy is converted to heat when it contacts a porous medium (due to viscous flow losses in the medium). Moreover, such loses tend to be maximized in areas where the velocity of the acoustic wave is maximum. Thus, it is desirable to match the airflow resistance of the absorption material to the velocity of such waves.
When an acoustic pressure wave reaches the interior surface of a cabinet wall, although it has an acoustical pressure, it has little or no velocity. Therefore, less absorption is achieved by the absorption materials that are positioned close to the interior walls of the cabinet. Furthermore, such prior approach of lining the interior surfaces of the cabinet walls requires the use of more absorption materials than would necessarily be required if the location of the absorption materials could be optimized relative to the location/position of the acoustical sound waves. The use of such additional insulation does little to improve the overall noise abatement results and adds significantly to the cost of the appliance. Such approach can also have the undesirable characteristic of retaining heat within the cabinet that could effect the operation of the electrically powered components mounted therein.
Such noise problems are not confined to washing machines. For example, similar problems occur with dishwashers and refrigerators. U.S. Pat. Nos. 4,985,106 and 5,044,705 to Nelson disclose insulation structures that can be employed in connection with dishwashers and water heaters in an effort to reduce the noise emanating therefrom. Such devices are applied to the top and sides of the dishwasher to form acoustical insulation over those portions of the dishwasher.
In view of the problems associated with prior noise abatement methods, there is a need for apparatuses that can be used to optimize the location of acoustical absorption materials within a cabinet enclosure to obtain an acceptable level of noise abatement while minimizing the amount of absorption material required.
There is another need for apparatus to advantageously alter the interior of a cabinet or enclosure that houses components that emit acoustical pressure waves to optimize the location of acoustical absorption materials within the cabinet.
There is yet another need for apparatus that is relatively inexpensive to produce, install and maintain for reducing the transmission of noise generated by an appliance such as an automatic clothes washing machine or a refrigerator.
There is still another need for apparatus that can be applied to a centrally located component of a machine that optimizes the amount of acoustical absorption while providing a desirable amount of localized thermal insulation thereto without retaining an undesirable amount of heat in the portions of the cabinet that house heat sensitive components.
In accordance with a particular preferred form of the present invention, there is provided an apparatus for reducing noise emitted from an appliance having a cabinet that supports one or more components that emit acoustic pressure waves. In a preferred form, the apparatus comprises a diffuser sized for placement within the cabinet or coupled to an outer portion of the cabinet. The diffuser has at least one deflection surface such that when the diffuser is coupled to the cabinet and located relative to at least one component, at least one deflection surface deflects at least one acoustical wave in a predetermined direction. In other preferred embodiments, the diffuser(s) are used in connection with absorber(s) coupled to the cabinet such that the diffuser(s) deflect acoustic pressure waves emitted from the component(s) into the absorber(s) wherein they are substantially absorbed.
The subject invention also preferably comprises a method for reducing the noise emitted by an appliance having a cabinet that supports at least one component that emits at least one acoustic pressure wave therefrom. Such method preferably comprises the actions of providing at least one absorber and positioning at least one diffuser relative to the component and the absorber to deflect at least one acoustic pressure wave to the absorber.
The subject invention also comprises a method of altering the internal geometry of an appliance cabinet that supports at least one component that emits at least one acoustic pressure wave. Such method preferably comprises the actions of coupling at least one absorber and at least one diffuser to the cabinet. The diffuser is preferably positioned relative to the component and the absorber such that the diffuser deflects at least one acoustic pressure wave to the absorber.
The present invention represents a unique and novel method and apparatus for reducing noise that is emitted from an appliance such as a washing machine or a refrigerator. The apparatus is relatively easy and inexpensive to manufacture and install and, as will be discussed in further detail below results in the reduction of emitted noise. These and other details, objects and advantages will become apparent as the following detailed description of the present preferred embodiments proceeds.